The invention relates to a device for increasing the security of a vehicle, and, more particularly, to a device for increasing the security of a vehicle having an automatic transmission, which is acted upon by an electric transmission control and a detection device for detecting a critical driving situation and generating a corresponding signal.
If it is determined that vehicle security is at risk, measures should generally be taken for continuously ensuring the vehicle security. In the following, a differentiation will be made between two groups of situations with respect to the vehicle security.
On the one hand, vehicle security may relate to a stable vehicle handling. Many methods and systems for improving the directional control are known.
For example, from German patent document DE 196 35 809 A1, a method and a system are known for improving directional control in the coasting operation, in which the transmission line is interrupted by disengaging a friction clutch when the difference of the rotational wheel speeds between the driven and non-driven wheels exceeds a certain threshold value. As a result, the directional control is increased in the coasting operation.
From German patent document DE 35 28 389 A1, a corresponding system is known for a wheel slip control.
U.S. patent document U.S. Pat. No. 5,362,287 describes a control method for an automatic clutch in the case of which the transmission line is interrupted when an excessive wheel slip is detected, the wheel slip being the result of an engine braking.
In the case of automatic transmissions, it is also recommended that, when the vehicle handling is unstable or during a swerving event, the “neutral” transmission position be engaged manually in order to more rapidly return the vehicle into a stable condition. However, very few drivers are capable of removing a hand from the steering wheel during a swerving event and moving the gear selector lever to the N position.
Another group of situations is represented by driving situations in the sense of accident situations. In accident situations, it is generally provided that, for safety reasons, a vehicle is to be stopped after an accident and any further vehicle movement is to be avoided.
For solving this problem various measures are known. For example, it is possible to interrupt the ignition or the fuel supply after an air bag is triggered, which may be used as an indicator with respect to an accident. The engine is then switched off after a corresponding event. However, it is also possible to interrupt the vehicle movement in a time-delayed manner. Furthermore, there is the risk that a disturbance exists in the engine timing unit and/or there is an interference in the signal transmission from the air bag control unit to the engine timing unit.
Furthermore, an air bag control unit is known from Japanese patent document JP 10103498, which provides a signal to a transmission control when an air bag is triggered. When the air bag is triggered, the transmission control shifts the transmission into a state with a low torque output.
It is an object of the present invention to further develop a system of the above-mentioned type for increasing the security in the case of a vehicle in order to ensure the vehicle safety in every case also during accidents and swerving events.
This object is achieved by a device for increasing the security of a vehicle having an automatic transmission, which is acted upon by an electric transmission control, and a detection device for detecting an accident or a swerving event and generating a corresponding signal. An analyzing device is provided to examine whether the generated signal reaches a certain value or exceeds a certain threshold. When the value is reached or the threshold is exceeded, the analyzing device causes the transmission control to interrupt the positive engagement of the transmission.
An essential idea of certain preferred embodiments of the present invention is the fact that the positive engagement in the transmission will be interrupted when a detection unit determines an accident or a swerving situation.
According to a first embodiment of the invention, the positive engagement in the automatic transmission will be interrupted by the electric transmission control in the event swerving starting at a defined swerving intensity. In a preferred embodiment, the transmission will then be shifted into the neutral position. In this manner, it is possible to interrupt the positive engagement in the transmission line independently and in the required manner in order to ensure high directional control of the vehicle.
According to an alternative embodiment of the invention, the transmission is controlled by the electric transmission control in the event of a triggering of an air bag and/or a rollover event such that the positive engagement in the transmission is interrupted. As a result, it is ensured that continued movement of the vehicle will be prevented even if the engine continues to run. In this case, the triggering of an air bag or the rollover event are used as an indication of the occurrence of an accident. A conclusion can be drawn with respect to the triggering of an air bag either by way of monitoring a crash sensor directly or by way of the reaction of an air bag control unit. In this sense, a triggering of an air bag is assumed even when signals are detected which lead to a triggering of an air bag.
In the above context, an embodiment of special interest is in the case wherein an automatically operable parking position is provided, which is also addressed by a control unit and which will be engaged when the vehicle has come to a stop after an air bag triggering operation and/or a rollover event. For indicating and including the vehicle speed, a normally existing vehicle speed sensor can be analyzed. Naturally, the parking position can also be engaged on the basis of other criteria. Furthermore, it is possible to immediately engage the parking position when the positive engagement is interrupted because of the air bag triggering operation or the rollover event. In this context, reference is also made to German patent document DE 196 25 019 A1 in which, among other things, an automatic activating of the parking position is described. By activating the parking position, rolling-away is effectively prevented after a stoppage of the vehicle.
According to another preferred embodiment, a transmission selection device is provided which has a defined rest position and, for selecting a driving position desired by the driver, can be directed out of its rest position into which it will then automatically return. When the positive engagement is interrupted or a shifting into the neutral position takes place on the part of the transmission, the driver will not be confused by different adjustments of the transmission selection device, on the one hand, and of the transmission, on the other hand. Also, no synchronization problems occur as a result of absent detent positions.
Additional embodiments are defined in the subclaims.
Two simple embodiments of the present invention will be explained in detail with respect to the attached drawings.